To examine how the use of intensive care varies, we compared 5,030 adult ICU admissions in 13 U.S. hospitals with 1,005 patients in two New Zealand (N.Z.) hospitals. Despite similar national demographic and hospital patient characteristics, there were substantial differences in the use of intensive care. The N.Z. hospitals designated 1.7% of their total beds for intensive care compared to 5.6% in the U.S. hospitals. The average age for N.Z. admissions was 42 compared to 55 in the U.S. (p less than .0001). The N.Z. ICUs admitted fewer patients with severe chronic failing health (N.Z. 8.7%, U.S. 18%) and following elective surgery (N.Z. 8%, U.S. 40%). Approximately half the N.Z. admissions were for trauma, drug overdose, and asthma while these diagnoses accounted for 11% of U.S. admissions. When controlled for differences in case mix and severity of illness, hospital mortality rates in N.Z. were comparable to the U.S. This study demonstrates substantial differences in patient selection among these U.S. and N.Z. ICUs that have equal technical and manpower capabilities and provide similar high-quality intensive care. Physicians from both countries justify the differences on medical criteria; however, both approaches to patient selection cannot be optimal. Additional outcome comparisons between acutely ill patients treated in the U.S. and N.Z. could help refine ICU selection criteria and improve the precision of clinical decision-making.